Topic
acid
3 articles across 3 sub-topics
Sub-topic
1 article
ACID Properties Explained: How SQL Databases Guarantee Atomicity, Consistency, Isolation, and Durability
TLDR: ACID is four orthogonal guarantees that every SQL transaction must provide. Atomicity says all-or-nothing: PostgreSQL implements it via WAL rollback; MySQL InnoDB via undo logs. Consistency says constraints always hold: the database rejects any...
Sub-topic
1 article
Isolation Levels in Databases: Read Committed, Repeatable Read, Snapshot, and Serializable Explained
TLDR: Isolation levels control which concurrency anomalies a transaction can see. Read Committed (PostgreSQL and Oracle's default) prevents dirty reads but still silently allows non-repeatable reads, write skew, and lost updates. Repeatable Read adds...
Sub-topic
1 article
ACID Transactions in Distributed Databases: DynamoDB, Cosmos DB, and Spanner Compared
TLDR: ACID transactions in distributed databases are not equal. DynamoDB provides multi-item atomicity scoped to 25 items using two-phase commit with a coordinator item, but only within a single region. Cosmos DB wraps partition-scoped operations ins...